28 - Differences in the Location of Herniated Lumbar Discs According to Dis...

#28 Differences in the Location of Herniated Lumbar Discs According to Disc Level

Epidemiology/Natural History

Poster Presented by: J.-W. Kwon

Author(s):

J.-W. Kwon (1)
C.-H. Lee (1)
S.-J. Hyun (1)
K.-J. Kim (1)
H.-J. Kim (1)
T.-A. Jahng (1)

(1) Seoul National Universtity Bundang Hospital, Department of Neurosurgery & Spine Center, Seongnam, Korea, Republic of

Abstract

Background: The direction of disc protusion and the migration of extruded disc are important in planning the surgical approach and extent in lumbar herniated intervertebral disc (HIVD). There is no report on the sagittal location of lumbar herniated discs according to disc level.

Objective: This study aimed to investigate the differences in the locations of HIVDs between upper (L1-2 and L2-3) and lower lumbar discs (L3-4, L4-5 & L5-S1).

Methods: The magnetic resonance imaging (MRI) results of 777 patients who underwent surgical procedures for lumbar HIVD from May 2003 to December 2011 were retrospectively reviewed. Forty-five, 71, 427 and 259 patients were included for upper lumbar HIVD, L3-4, L4-5 and L5-S1 HIVD, respectively. The locations of the herniated disc were classified as central, subarticular, foraminal and extraforaminal in the horizontal plane and upward, disc level, downward and bidirectional in the sagittal plane.

Results: The most frequent location of lumbar HIVD in the horizontal plane was the central zone, followed by the subarticular zone, regardless of the level. There was no statistical correlation between the affected level and the location of the lumbar HIVD in the horizontal plane. Upward migration tended to be more common in the upper lumbar HIVD, whereas downward migration was more frequent in lower lumbar HIVD with statistical significance.

Conclusion: The direction of sagittal migration in upper lumbar HIVD differed from that in lower lumbar HIVD. The differences in the anatomical characteristics of lumbar vertebrae and biomechanical properties at each level may explain these results.